Strong box



FIG. 1 is a perspective view of a strong box showing my new design;

FIG. 2 is a side view of the design of FIG. 1;

FIG. 3 is a top plan view of the design of FIG. 1;

FIG. 4 is a bottom plan view of the design of FIG. 1;

FIG. 5 is an internal plan view of the cover of my new design;

FIG. 6 is an internal plan view of the base of my new design; and,

FIG. 7 is an exploded side view of the design of FIG. 1.

The ornamental design for strong box, as shown and described.